I have experienced what I consider unfair billing practices from AT&T on numerous occasions. I travel a lot for business and am conservative with international calls.
The package I used and extras like unlimited texting, etc did not result in the savings I thought. When returning to the USA and finding bills over $1000 I get a little upset. On 4 separate occasions I called customer service to complain about the unexpected charges for things like - my phone automatically checking for emails in a foreign country ~ $400 or my software mistakenly trying to download all of my emails from gmail.com using my aircard ~$1200. On each occasion I complained vigorously to supervisors about the billing practices being predatory and unfair and had the bill reduced considerably, by more than 50%.
So, I got tired of negotiating my phone bill every month and feeling that I had been continuously taken advantage of. I longed for an honest company that keeps it simple and affordable but my impression of AT&T is that they keep it complicated and expensive purposely to increase revenue. My solution was to pay AT&T's outrageous cancellation penalties and go to a OneSim prepaid international phone where I can see exactly what is going on with my account, pay considerably less for calls and do not get surprises. I ported my number to phone.com who have a very affordable $5/mo) forwarding and message service.
Now I am quite happy and also use a MagicJack as backup. I am finished with the big carriers and the games they play - the administrations would do well to regulate these guys and force fair business practices as they have moved towards with credit cards and health insurers.